code: def check_nonnegativity(method, h1, h2):
      """distance between two samples must be >= 0.0"""
  
      assert method(h1, h2) >= 0.0
  
file_path: medpy/tests/metric_/histogram.py
imports: import numpy
  from hypothesis import given, strategies, assume, Verbosity, note, event
  from hypothesis import settings
  from medpy.metric import histogram
label_desc: Use image node_id 6 for calling a global function with example usage: check_nonnegativity(method, h1, h2) without return types